IADR Abstract Archives
High-strength, Low-shrinkage Composite With Potential to Self-bond to Dentine
Objectives: This study was performed to develop ivory dentine adhesion models that could help in the assessment of a high strength, low shrinkage and self-bonding dental composite.
Methods: UDMA:TEGDMA (3:1) was mixed with 5 wt% adhesive monomer (HEMA or 4-META). This was combined with silane treated glass particles. PLR was 4:1. Mechanical properties of composites 3 commercial (Z250, Gradia Direct, & Vertise Flow), and 2 experimental (C-HEMA, & C-4META) were determined using biaxial flexural test. Samples were made of 1 mm thickness, and 10 mm diameter. Composite bonding to dentine (ivory & human), with and without use of acid pre-treatment and / or the adhesive ibond, were assessed using a shear bond test. Brass tubes of 3 mm diameter and 6 mm deep were used. Composites were applied in 2 mm increments. All the composites were cured for 40 s. Furthermore, micro gap formation after restoration of 3 mm diameter cavities in dentine was assessed by SEM.
Results: Experimental composite strengths (168 MPa) were higher than commercial (77 – 158 MPa). With ibond use, average shear bond strengths were 30 and 26 MPa with and without acid etching. This was irrespective of whether the dentine was ivory or human. With no ibond, average bond strength was 6 MPa for conventional composites. This, however, increased to 14 MPa with a commercial flowable composite or upon addition of low levels of an acidic monomer 4-META to the experimental composite. The C-4META composite additionally reduced micro-gap formation (0- 2 µm) with dentine. While in other commercial and experimental composites a micro-gap of 5-20 µm were seen using different dentine pre-conditionings.
Conclusions: Improved bonding and mechanical properties were seen with C-4META composite. The high PLR would reduce polymerization shrinkage. This would additionally help to reduce composite failures due to recurrent caries or fracture respectively.
Methods: UDMA:TEGDMA (3:1) was mixed with 5 wt% adhesive monomer (HEMA or 4-META). This was combined with silane treated glass particles. PLR was 4:1. Mechanical properties of composites 3 commercial (Z250, Gradia Direct, & Vertise Flow), and 2 experimental (C-HEMA, & C-4META) were determined using biaxial flexural test. Samples were made of 1 mm thickness, and 10 mm diameter. Composite bonding to dentine (ivory & human), with and without use of acid pre-treatment and / or the adhesive ibond, were assessed using a shear bond test. Brass tubes of 3 mm diameter and 6 mm deep were used. Composites were applied in 2 mm increments. All the composites were cured for 40 s. Furthermore, micro gap formation after restoration of 3 mm diameter cavities in dentine was assessed by SEM.
Results: Experimental composite strengths (168 MPa) were higher than commercial (77 – 158 MPa). With ibond use, average shear bond strengths were 30 and 26 MPa with and without acid etching. This was irrespective of whether the dentine was ivory or human. With no ibond, average bond strength was 6 MPa for conventional composites. This, however, increased to 14 MPa with a commercial flowable composite or upon addition of low levels of an acidic monomer 4-META to the experimental composite. The C-4META composite additionally reduced micro-gap formation (0- 2 µm) with dentine. While in other commercial and experimental composites a micro-gap of 5-20 µm were seen using different dentine pre-conditionings.
Conclusions: Improved bonding and mechanical properties were seen with C-4META composite. The high PLR would reduce polymerization shrinkage. This would additionally help to reduce composite failures due to recurrent caries or fracture respectively.